Field of the Disclosure
The present disclosure relates to an imprint apparatus, and a method of manufacturing an article.
Description of the Related Art
An imprint technique is being put into practical use as one of the lithography techniques for manufacturing an article, such as a semiconductor device.
In imprint processing in the air, pressing of a resin with a mold tends to cause a bubble to be trapped between the mold and the resin. If the resin is cured while the bubble is left, a formed pattern may have an unfilled defect.
To eliminate or reduce such an unfilled defect, the time (hereinafter, “filling time”) required for filling with the resin has to be set to a long time so that the mold maintains contact with the resin until the trapped air dissipates away from a shot or is dissolved in the resin. A reduction in throughput of an apparatus caused by extending the filling time is one of the disadvantages of the imprint technique.
As a measure to reduce an unfilled defect or the filling time, PCT Japanese Translation Patent Publication No. 2011-514658 discloses introduction of helium that has a high molecular diffusion rate or carbon dioxide that is readily dissolved in resin. However, further improvement is required to reduce the filling time and increase the throughput of an apparatus.
Japanese Patent No. 3700001 discloses a configuration in which a space including the whole of a substrate or an imprint processing target region is exposed to a condensable gas in order to further reduce the filling time. In this configuration, condensing the condensable gas trapped between a mold and resin can reduce the filling time and eliminate or reduce an unfilled defect. Hiroshima, Journal of Vacuum Science and Technology B 27(6) (2009), 2862-2865, reports that the use of 1,1,1,3,3-pentafluoropropane (hereinafter, simply referred to as “pentafluoropropane”), a kind of condensable gas, enables a reduction in force (hereinafter, “release force”) with which a mold is separated or released from cured resin. Reducing the release force can eliminate or reduce deposition of resin on the mold, thus reducing a transfer defect. Furthermore, Hiroshima, Journal of Photopolymer Science and Technology Volume 23, Number 1 (2010), 45-50, reports a phenomenon in which the viscosity of resin is lowered by pentafluoropropane. The lower the viscosity of resin is, the easier the resin spreads over a substrate. Thus, the filling time can be reduced. In addition, Japanese Patent Laid-Open No. 2009-052595 discloses an apparatus and method for stably supplying a low vapor pressure liquefied gas, such as HF, ClF3, BCl3, SiH2, Cl2, or WF6, which is used in a semiconductor factory. As described in Japanese Patent Laid-Open No. 2009-052595, to prevent the low vapor pressure liquefied gas from being liquefied in gas supply pipes, the liquefied gas is transferred in a gas state from a cylinder filled with the low vapor pressure liquefied gas to a secondary storage, the liquefied gas is reliquefied and is then vaporized in the secondary storage, and after that, the liquefied gas is supplied to the apparatus. The pipes are temperature-controlled to prevent the gas from being liquefied in the pipes.
Pentafluoropropane, a kind of condensable gas, has an effect in reducing the release force, an effect of lowering the viscosity of resin, and is useful to reduce the filling time, unfilled defects, and transfer defects. Typically, pentafluoropropane, serving as a low vapor pressure condensable gas, is stored in a liquid state in a container, the gas is vaporized in the container, and the gas is then transferred to an imprint apparatus. As regards energy to transfer the condensable gas vaporized in the container to the imprint apparatus, the vapor pressure of pentafluoropropane, or an extremely low pressure alone is used as energy. Typically, external energy produced by a pump or the like is not used. In an imprint apparatus used for a semiconductor manufacturing process, for example, a mass flow controller for precisely regulating the flow rate of pentafluoropropane and a cleaning filter are arranged in a pipe. Furthermore, a container is disposed outside a clean room in a semiconductor factory and the pipe is accordingly long. This increases a pressure loss in the pipe, causing pentafluoropropane to be liquefied in the pipe. Disadvantageously, it is difficult to stably supply the gas to the imprint apparatus. According to the method disclosed in Japanese Patent Laid-Open No. 2009-052595, the condensable gas is transferred in the gas state to the secondary storage disposed in the vicinity of the imprint apparatus, the gas is reliquefied in the secondary storage, and the gas is then transferred to the apparatus. This achieves stable supply of the condensable gas to the apparatus. However, if a cleaning filter is disposed in the pipe, it is difficult to prevent the condensable gas from being liquefied in the pipe because the filter has a high pressure loss. Unfortunately, it is difficult to stably supply the condensable gas.